Exhaust cap



Nov. 9, 1965 R. s. FARR 3,216,343

EXHAUST CAP Filed Aug. 5, 1963 2 Sheets-Sheet 1 INVENTOR. RICHARD S. FARR 34 35 BY 7 F G. 6. 6

ATTORNEYS.

Nov. 9, 1965 R. s. FARR 3,216,343

EXHAUST CAP Filed Aug. 5, 1963 2 Sheets-Sheet 2 @zob E U 3 Fig 40M b INVENTOR. RICHARD S. FARR ATTORNEYS United States Patent 3,216,343 EXHAUST CAP Richard S. Farr, Los Angeles, Calif., assignor to Farr Company, El Segundo, Califl, a corporation of California Filed Aug. 5, 1963, Ser. No. 300,004 8 Claims. (Cl. 98-59) This is a continuation-in-part of application Serial No. 120,067 filed June 27, 1961 and now abandoned.

This invention relates to closures for exhaust pipes and, in particular, is directed to a cap which may be installed on the upstanding end of a vertical exhaust pipe.

It has generally been found advantageous to close the open end of an internal combustion engine exhaust pipe for various reasons. For example, in many installation-s such as tractors or large trucks, the exhaust pipes are mounted in a vertical position with their open ends projecting upwardly. Without any cap on such an upwardly facing open end rain, snow or foreign objects may enter the exhaust pipe with resultant possible damage to the engine or exhaust system. This hazard is particularly a problem when the engine is not running since, for instance, any rain entering the exhaust pipe while the engine is running would be vaporized immediately and exhausted without appreciable damage to the system.

For proper protection an exhaust pipe cap should close immediately upon stopping of the engine but for operation it should open immediately upon starting of the engine. Further, it is preferable that the cap open and close without any special or additional elfort on the part of the operator. Also, the exhaust cap should offer a very minimum of resistance to the flow of exhaust gases while the engine is running since any increase in resistance results in a decrease in efiiciency of the engine.

In the common type of exhaust pipe cap a circular cover fits over the end of the pipe and is hinged at the edge of the pipe for swinging upward to an open position when gases are exhausted from the pipe. A counterweight is usually attached to the cover and projects outwardly from the exhaust pipe beyond the axis of the hinge so that the weight of the cover is counterbalanced for ease of opening. With such a construction the amount of force required from the exhaust gases to open the cover is greater than the force required to keep the cover open. However, the forces developed by the exhaust are greater when the engine is running fast than when it is idling and therefore when the engine is idling the cover tends to close. This has been found objectionable with conventional covers since the cover actually vacilates between the open and closed positions when the engine is idling thereby causing a fluctuation in the back pressure on the exhaust system as well as a clattering noise. This repeated opening and closing also objectionably increases the Wear on the hinge.

In some intake air filtering systems, the exhaust manifolding is modified to form an aspirator whereby the exhaust gases act to draw or bleed air and dirt out of the air filter. For pro-per operation the flow of exhaust gases and back pressure on the system must be relatively uniform. With a common type of exhaust pipe cap this is not possible when the engine is idling.

Accordingly, it is a principal object of this invention to provide an improved exhaust pipe cap for the upstanding open end of a vertical exhaust pipe of the type where- Patented Nov. 9, 1965 in the cap is normally closed and may be opened by the mere fiow of exhaust gases out of the exhaust pipe.

Another object of this invention is to provide an exhaust cap for a vertical exhaust pipe wherein two semicircular cover members are pivoted about an axis across the top of the cap whereby the members each swing upwardly and inwardly to an open position upon the flow of exhaust gases out of the pipe.

A further object of this invention is to provide an exhaust cap for a vertical exhaust pipe wherein the cover is normallyclosed, may be opened with a minimum of exhaust gas flow, and requires a very minimum flow of exhaust gases to maintain the cover in a full open position.

Another and more detailed object is to provide an exhaust cap for a vertical exhaust pipe wherein two semi-circular members close the top of the exhau-stpipe and are pivoted on a diametric edge to swing upwardly and inwardly to an open position, and are provided with counterweights for promoting ease of opening but insuring.

closing upon the stopping of the flow of exhaust gases.

Still another object of this invention is to provide a pivoted and counterbalanced type exhaust cap for a vertical exhaust pipe wherein the counterbalance weights are positioned in the stream of exhaust gases when the cap is open to produce an aerodynamic drag on the weights tending to maintain the cap in open position.

A still further object of this invention is to provide a pivoted type exhaust cap with a surface projecting into the stream of exhaust gases when the cap is in open position for assisting in maintaining the cap open, particularly under low rates of exhaust gas flow, without imposing a substantial restriction on exhaust gas flow.

Other and more detailed objects and advantages of this invention will appear from the following description and the accompanying drawings.

In the drawings:

FIGURE 1 is an elevation view showing the device of this invention installed on a vertical exhaust pipe of a truck.

FIGURE 2 is a plan view of the device of this invention with portions sectioned for clarity.

FIGURE 3 is a sectional elevation view taken substantially on the line 33 and showing the open position of the device in phantom lines.

FIGURE 4 is a fragmentary sectional elevation view taken substantially on the line 44 of FIGURE 3.

FIGURE 5 is a fragmentary sectional elevation view similar to FIGURE 3 showing a modified form of hinge construction of this invention.

FIGURE 6 is an elevation view similar to FIGURE 3 illustrating a modified means for clamping the device to an exhaust pipe.

FIGURE 7 is a plan view of a modified form of the device of this invention.

FIGURE 8 is a sectional elevation of the modified form of FIGURE 7 taken substantially on the line 88 of FIGURE 7.

FIGURE 9 is a view similar to FIGURE 8 illustrating the device in open position under a very low rate of exhaust gas flow.

FIGURE 10 is a perspective view of a counterweight assembly that is attached to each of the two cover members of the modified form of device shown in FIGURES 7, 8 and 9.

Referring now more particularly to FIGURES 1-4, the exhaust cap assembly, generally designated 10, is installed on the upper end of the exhaust pipe 11 by any convenient means, such as hereinafter described. The assembly is comprised of a cylindrical housing 12 having an inner surface 13 fitting the external surface of the exhaust pipe 11 and a pair of semi-circular cover members 14 and 15 pivotally mounted on the upper end of the housing 12.

In order to provide a pivotal support for the cover members 14 and 15, a pair of tabs 16 and 17 are mounted on the exterior of the housing 12 by any convenient means such as weld 18. The tabs 16 and 17 are circumferenidly support a shaft 20. The shaft 20 is fixedly mounted in the tabs 16 and 17 such as byweld 21 and is so oriented as to be perpendicular to and pass through the axis of the cylindrical housing 12.

' The cover members 14 and 15 are each provided with a pair of hinge elements 22 and 23 along their diametric edges 24 and 25, respectively, for encircling the shaft 20.

' In order to promote the ease of opening of the cover members, counterweight assemblies 26 and 27 are mounted on the lower side of the cover members 14 and 15, respectively. The counterweight assemblies each are comprised of an element 28 fixed'to the underside of the cover member and extending toward the-underside of the other cover member and a weight 29 fixed to the element 28 and positioned directly beneath the other cover member. As can best be seen in FIGURES Z and 4, these counterweight assemblies 26 and 27 are otfset'from each other to avoid'interference therebetween upon opening and closing of the cover members.

Each of the cover members may be provided with a downwardly extending lip portion 30 for rigidity and maximum effectiveness against the intrusion of rain, snow or foreign objects into the exhaust pipe.

As illustrated by the phantom lines in FIGURE 3, when exhaust gases are discharged from the exhaust pipe 11, the cover members 14 and 15 pivot about the shaft 20 and assume a vertical position to permit escape of the gases. When in a vertical position, each of the cover members and their attached'counterweightassemblies are totally on one side of the axis of the shaft 20, thereby tending to pivot about the shaft 20 to close against the.

upper end of the housing 12 when the exhausting of the gases is discontinued. The counterweight assemblies and semi-circular cover members are each of a magnitude of weight and so oriented relative to the axis of shaft20' as to cause the cover members 14 and 15 to .be in a normally closed position against the upper end of the hous-. ing 12 when the-axis of that housing is in a vertical position. The weight of the cover members are sufficiently counterbalanced by weights 29 to promote ease ofv opening of the cover members when gases are being exhausted from pipe 11.

The opening of the cover members 14 and 15 by the flow of exhaust gases causes the counterweights 29 tobe positioned within the stream .of upwardly flowing gases thereby producing an aerodynamic drag force on the counterweights in an upward direction. This upwardly drag force on each counterweight is in a direction tending to open the attached cover member or maintain the cover member in open position. Or, in other words, this upward aerodynamic drag force opposes and tends to counteract the gravity force urgingthe cover member in a closed direction by reason of the cover member and counterweight being on the same side of thepivot shaft 20; Thus, it has been found that the cover members 14 and 15 will be maintained in open position under low rates of exhaust gas flow, such as under engine idling conditions, but will close when gas flow discontinues. Moreover, the cover members openand close smoothly due to the aerodynamic effects thereby avoiding abrupt changes in back pressureor clattering caused by the cover members.

The modified form of my invention shown in FIGURE 5 is similar to the heretofore described form except that the tabs 16a have longer projecting portions 19a and therefore the shaft 20a is located at a greater axial distance from the end of the cylindrical housing 12a. In addition, upwardly projecting lip portions 31 and 32 are provided on the cover members 14a and 15a along their diametric edges 24a and 25a, all respectively. These upstanding lips 31 and 32 further inhibit any intrusion of rain, snow or foreign objects into the exhaust pipe 11.

The exhaust cap assembly 10 is removably secured to the exhaust pipe 11 by any convenient means such as by a set'screw 33 threadedly received in the housing 12 and tab 16 and engaging the outer surface of the exhaust pipe 11. In the modified form of my invention, shown in FIGURE 6, the cylindrical housing of the exhaust cap assembly 10 is constructedof two halves 34 and 35 each having a pair of radially extending projections 36 with holes therethrough and a pair of bolt assemblies 37 extended through suchholes in the projections to clamp the two halves onto the exterior of the exhaust pipe 11. In all other respects the modified form of this invention shown in FIGURE 6 may be identical to either the preferred form illustrated in FIGURES 2, 3 and 4 or the modified hinge form shown in FIGURE 5.

Referring now to the modified form of my invention shown in FIGURES 7-10, the general construction of the exhaust cap'assembly, generally designated 10b, may be substantially similar to exhaust cap assembly 10 or the modifications illustrated in FIGURES 5 and 6. Tabs 16b and 17b are mounted on the cylindrical housing 12b and extend upwardly to support the diametric shaft 20b. The semi-cylindrical cover members 14b and 15b are pivotally mounted on shaft 20b by hinge elements 22b and 23b. A pair of aerodynamic counterweight assemblies, generally designated 26b and 27b, are mounted on the underside of cover members 14b and 15b, respectively. Each counterweight assembly includes an element 28b secured to the cover member and a weight 29b secured to element 28b. As with exhaust cap assembly 10, the aerodynamic counterweight assemblies 26b and 27b are positioned below the cover members and below the pivot shaft 20b and the weights 29b of each extend below the other cover member. Each element 28b is provided with an aerodynamic tab 40 positioned to extend downwardly from the underside of the cover member and approximately parallel to the shaft 20b. Thus, as exhaust gases escape through the open or partially open cover members 14b and 15b the gases confront a surface 41 of each tab 40 thereby producing an aerodynamic force on each cover member tending to hold the cover member open. The tabs 40 are spaced from pivot shaft 20b as shown so that the tabs 40' are above the top or Open end of the cylindrical housing 12b when the cover members 14b and 15b are open thereby causing negligible back pressure on the exhaustgases and yetkeeping the cover members open. In this embodiment, as in assembly 10, the weights are positioned in the stream of exhaust gases to produce an aerodynamic drag tending to maintain the cover members in open position.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth or to the details illustrated in the the drawings, but my invention is of the full scope of the appended claims.

I claim:

1. In a cap for the upstanding open end of a vertical exhaust pipe, the combination of: a cylindrical housing having upper and lower open ends, the said lower end for mounting on the open end of the exhaust pipe, a pair of tabs mounted on the exterior of said housing, said tabs being diametrically spaced and having a portion projecting axially beyond said upper end, a-shaft mounted on-said projecting portion'of the tabs perpendicular to the axis of the housing, a pair of semi-circular members fitted over said upper end of the housing, each said member having a diametric edge, said edges being adjacent each other and parallel to said shaft, hinge means along each of said edges projecting upwardly for pivotally mounting said members on said shaft, and a counterweight means on each member within said housing and extending past the said diametric edge of that member whereby the members are normally substantially horizontal for closing the upper end of the housing and may be pivoted to a vertical or open position.

2. In a cap for the upstanding open end of a vertical exhaust pipe, the combination of: a cylindrical housing having upper and lower open ends, the said lower end for encircling the open end of the exhaust pipe, means for clamping said housing on the exhaust pipe, a pair of tabs mounted on the exterior of said housing, said tabs being diametrically spaced and having a portion projecting upward beyond said upper end, a shaft mounted on said projecting portion of the tabs perpendicular to the axis of the housing, a pair of semicircular members fitted over the said upper end of the housing, each said member having a diametric edge with an upwardly extending lip, said edges being adjacent each other and parallel to said shaft, hinge means along each of said edges projecting upwardly from said upwardly extending lips for pivotally mounting said members on said shaft, and a counterweight means mounted on each member within said housing and extending past the said diametric edge of that member whereby the members are normally substantially horizontal for closing the upper end of the housing and may be pivoted to a vertical or open position.

3. In a cap for the upstanding open end of a vertical exhaust pipe, the combination of: a cylindrical housing having upper and lower open ends, the said lower end for mounting on the open end of the exhaust pipe, a pair of tabs mounted on the exterior of said housing, said tabs being diametrically spaced and having a portion projecting upward beyond said upper end, a shaft mounted on said projecting portion of the tabs perpendicular to the axis of the housing, a pair of semi-circular members fitted over said upper end of the housing, downwardly projecting lips around the periphery of each member outside of the said housing, each said member having a diametric edge with an upwardly projecting lip, said edges being adjacent each other and parallel to said shaft, hinge means along each of said edges projecting upwardly for pivotally mounting said members on said shaft, and a counterweight means mounted on each member and extending within said housing past the said diametric edge of that member whereby the members are normally substantially horizontal closing the upper end of the housing and may be pivoted to a vertical or open position.

4. In a closure for the upstanding open end of a vertical exhaust pipe, the combination of: a pair of semicircular members cooperating to form a circular cover over the open end of the exhaust pipe, each member having a diametric edge adjacent such edge of the other member, means pivotally mounting said members on the exhaust pipe for pivoting about an axis substantially parallel to and above the said diametric edges and counterweight means mounted on each said member having a weight positioned for nearly balancing said member when said member is in a closed position and for being positioned in the upwardly flowing exhaust gas stream when said member is in an open position to cause an aerodynamic drag force on said weight tending to maintain said member in open position.

5. In a closure for the upstanding open end of a vertical exhaust pipe, the combination of: a pair of semicircular members cooperating to form a circular cover over the open end of the exhaust pipe, each member 6 having a diametric edge adjacent such edge of the other member, means pivotally mounting said members on the exhaust pipe for pivoting about an axis substantially parallel to and above the said diametric edges, counterweight means mounted on each said member having a weight positioned for nearly balancing said member when said member is in a closed position and for being positioned in the upwardly flowing exhaust gas stream when said member is in an open position to cause an aerodynamic drag force on said weight tending to maintain said member in open position, and means on each said semicircular member having a surface extending downwardly from the underside of the member and positioned relatively parallel to said axis for confronting exhausting gases to produce an aerodynamic force tending to open said member.

6. In a closure for the upstanding open end of a vertical exhaust pipe, the combination of: a pair of semicircular members cooperating to form a circular cover over the open end of the exhaust pipe, each member having a diametric edge adjacent such edge of the other member, means pivotally mounting said members on the exhaust pipe for pivoting about an axis substantially parallel to and above the said diametric edges, counterweight means mounted on each said member having a weight positioned for nearly balancing said member when said member is in a closed position and for being positioned in the upwardly flowing exhaust gas stream when said member is in an open position to cause an aerodynamic drag force on said weight tending to maintain said member in open position, and means on each said semi-circular member having a surface extending downwardly from the underside of the member and positioned relatively parallel to said axis for confronting exhausting gases to produce an aerodynamic force tending to open said member, said surface being positioned a substantial radial distance from said axis and next to said member for causing said surface to .be substantially above the open end of the exhaust pipe when said member is in the open position.

7. In a closure for the upstanding open end of a vertical exhaust pipe, the combination of: a pair of semicircular members cooperating to form a circular cover over the open end of the exhaust pipe, each member having a diametric edge adjacent such edge of the other member, means pivotally mounting said members on the exhaust pipe for pivoting about an axis substantially parallel to the said diametric edges, counterweight means mounted on each said member for nearly balancing said member in the closed position and producing substantial force tending to close said member in the open position, and said counterweight means having means positioned in the stream of exhaust gases when in open position to produce aerodynamic forces tending to maintain said members in open position.

8. In a closure for the upstanding open end of a vertical exhaust pipe, the combination of: a pair of semicircular members cooperating to form a circular cover over the open end of the exhaust pipe, each member having a diametric edge adjacent such edge of the other member, means pivotally mounting said members on the exhaust pipe for pivoting about an axis substantially parallel to and above the said diametric edges, an element mounted on the underside of each said member and having a tab positioned with a surface thereof extending downwardly and positioned relatively parallel to said axis for confronting gases exhausted past that said member, and an elongated weight secured to each said element and extending laterally beyond said axis for nearly balancing said member, said weight and said surface being urged upwardly by said exhaust gases for maintaining said member in the open position.

(References on following page) 7 References Cited by the Examiner 2,641,987

UNITED STATES PATENTS. gggggi 5/78 B IOCk -7 220'-32 3 009 473 4/18 Wolf 9s'--11'9 12/18 Cathey 220-35 3 111 301 4/25 O'sbun 98-"43" s/47 Curphy 98- -59 1/50 Taylor 98 -59 146,586" 5/50 Lukes 98-59" 1,170,671 5/51 Artis 98-59' 5/53 Harmon.

6/53 Burgan 98-43 7/54 Cook 9843 10/56 Paley et a1. 220-35 1 1/61 Hennen 220-35 8/62 Kimberley 9843 11/63 Rilegsegger 98119 X FOREIGN PATENTS 5/52' Australia. 9/ 5 8 France.

ROBERT 'A': OLEARY, Primary Examiner. 

1. IN A CAP FOR THE UPSTANDING OPEN END OF A VERTICAL EXHAUST PIPE, THE COMBINATION OF: A CYLINDRICAL HOUSING HAVING UPPER AND LOWER OPEN ENDS, THE SAID LOWER END FOR MOUNTING ON THE OPEN END OF THE EXHAUST PIPE, A PAIR OF TABS MOUNTED ON THE EXTERIOR OF SAID HOUSING, SAID TABS BEING DIAMETRICALLY SPACED AND HAVING A PORTION PROJECTING AXIALLY BEYOND SAID UPPER END, A SHAFT MOUNTED ON SAID PROJECTING PORTION OF THE TABS PERPENDICULAR TO THE AXIS OF THE HOUSING, A PAIR OF SEMI-CIRCULAR MEMBERS FITTED OVER SAID UPPER END OF THE HOUSING, EACH SAID MEMBER HAVING DIAMETRIC EDGE, SAID EDGES BEING ADJACENT EACH OTHER AND PARALLEL TO SAID SHAFT, HINGE MEANS ALONG EACH OF SAID EDGES PROJECTING UPWARDLY FOR PIVOTALLY MOUNTING SAID MEMBERS ON SAID SHAFT, AND A COUNTERWEIGHT MEANS ON EACH MEMBER WITHIN SAID HOUSING AND EXTENDING PAST THE SAID DIAMETRIC EDGE OF THAT MEMBER WHEREBY THE MEMBERS ARE NORMALLY SUBSTANTIALLY HORIZONTAL FOR CLOSING THE UPPER END OF THE HOUSING AND MAY BE PIVOTED TO A VERTICAL OR OPEN POSITION. 